This invention relates to semiconductor devices and, more particularly, to semiconductor light emitting devices, such as lasers, which have improved far field divergence and improved power capability.
A typical semiconductor laser employs a single-stripe geometry if intended for low power (low threshold) applications, and multiple stripes for coupled-stripe higher power operation. In either case the thin horizontal ("flat") geometry of the semiconductor laser required for low threshold and stable fundamental mode operation leads to a relatively large vertical (.theta..sub..perp.) beam width. To reduce the vertical beam spread requires some method of vertically expanding the optical mode. A large optical cavity expands the waveguiding region but can introduce problems in ensuring zero-order mode operation. Enlarging the active region, however, reduces the likelihood of higher order transverse modes in a waveguide of fixed size.
Accordingly, there is a need for development of a practical semiconductor laser device which has less far field divergence without unduly sacrificing other laser properties. It is among the objects of the present invention to address this need.
It is also among the objects of the present invention to provide semiconductor light emitters, particularly lasers, having improved power output and which can be configured in two dimensional arrays.